The present invention is in the technical field of optics. More particularly, the present invention is in the technical field of lenses. Lenses are commonly made by shaping an optical material such as glass. The weight of such lenses increases strongly with diameter making them expensive and prohibitively heavy for applications requiring large area. Also the quality of a lens typically decreases with increasing size. To achieve desired features such as high-quality imaging, conventional lenses sometimes have curved surfaces that are non-spherical. The need to grind and polish conventional lenses with non-spherical surfaces can make such lenses extremely expensive. Segmented lenses such as Fresnel lenses are relatively thin, however, the structural discontinuities result in severe aberrations. Uses of holographic lenses are limited by the compromise of efficiency, spectral bandwidth and dispersion. Thus, there is a need for lenses that could be obtained in the form of thin film structurally continuous coatings on a variety of substrates.
Thus, the need exists for solutions to the above problems with the prior art.